Winning blow: king to a2 (b1·36)
c9-24235naming tag (square·N)Opens in the app if installed, otherwise downloads the APK.
The tactical motive
Chess960 twist: use the unusual starting setup of the pieces.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 1390 ShuffleRating — club-player level.
White to move — find the best continuation
How to recognize this tactic
In Chess960 the pieces start on unfamiliar squares, so tactics appear earlier and from unusual angles. Do not trust classical patterns — read the actual lines of the bishops, the rooks and the queen from where they really stand in this position.
This position hides a concrete tactic that wins material or mates. Start with the most forcing candidate moves — checks, captures and threats — and calculate each to a clear end before choosing; the winning line is usually the one the opponent cannot meet.
General method: before you move, list the forcing candidates — every check, every capture, every direct threat — and calculate those first. The solution to a tactic is almost always among them.
Position on the board
White: king b1, queen d5, rook c2, bishop g1, pawn b2 h2 g3 a4 e5.
Black: king c8, queen e1, rook g6, bishop g5, pawn c4 a5 c5 f5 h7.
9 white and 9 black pieces are on the board; the puzzle position arises after move 37.
The position in numbers
Material is level — 22 points of pieces on each side (pawn = 1, knight and bishop = 3, rook = 5, queen = 9).
The white king stands on b1, the black king on c8.
It is White to move on move 37, with 3 legal replies to weigh — only the line that keeps the advantage solves the puzzle. White are in check right now, so every reply must answer the check.
White keeps 5 pawns, Black 5. Files fully open (no pawns of either colour): d — natural highways for the rooks and queen. Half-open for White: c, f.
The White king has 1 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
37. Ka2 Qe4 38. Qxe4 fxe4 39. Rxc4 Kd7 40. Rxe4
Why it works
- Great move! king to a2 keeps the pressure (+3.0).
- Spot on — queen to e4 (+3.0).
- Precise: rook to c4 is the top choice (+3.1).
- Great move! rook to e4 keeps the pressure (+3.2).
- You reach a winning position (+3.2).
- If instead Qe4, then Qxe4 and you win the queen.
Move by move
- 37. Ka2 — king to a2
- Qe4 — queen to e4
- 38. Qxe4 — queen to e4 (capture)
- fxe4 — pawn to e4 (capture)
- 39. Rxc4 — rook to c4 (capture)
- Kd7 — king to d7
- 40. Rxe4 — rook to e4 (capture)
Types in this puzzle
Decoy
A sacrifice lures the king or a piece onto a fatal square.
A decoy is the mirror image of deflection: you sacrifice to drag the king or a piece onto a fatal square. The classic is a queen or rook sac whose capture pulls the king into a knight fork, a discovered check or mate. Find the square where the target will be hit, then find the offer it cannot refuse. Calculate to the very end — a decoy only works when the follow-up is forced.
Only move
Everything else loses — find the only move that holds.
An only move is a position where everything loses except one single continuation. You cannot play "by hand" here: run through fundamentally different defenses — run away, block, trade, counterattack — and discard the ones that fail. The hallmark of these puzzles is that the obvious moves lose quickly while the solution often looks strange. First understand exactly what the threat is — then the one saving move reveals itself.
Simplification
Trade the heavy pieces and steer into a won endgame.
Simplification is how you convert an advantage: by trading queens and rooks you extinguish the counterplay and steer the game into a won endgame. The rule is simple — the side with extra material trades pieces but keeps pawns. Look for exchanges once the material is already won and your opponent is still rattling threats. The mistake is avoiding the queen trade and letting him muddy the water forever.
About this position
These pieces come from starting position #555.
SP-555 · BastionGuard — King shifted to c or f, knights kept clear of the edges — 168 positions in all.
The king starts on c1, the rooks on a1 and g1, the queen on f1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
One second-rank pawn starts with no defender at all: h2.
The setup belongs to the BastionGuard family; read right to left it becomes position 497.
The engine's main line opens with g4.
Morozov Balance Index: 51 of 100 — class B — balanced. Engine evaluation of the starting position: +26 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #555Provenance
Mined from the project's engine self-play games.
Pack 010 · SP-555
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